I would say its definitely ribbon... Look at the corners. You couldn't get the design to go over the corners like that by stencilling straight on. Either it is a) fabric ribbon b) edible ribbon printed eg by lucks, or home edible printer system or c) stencilled on a fondant ribbon (least likely option as it is so perfect)

if you look at the smaller right hand corner paper, you can tell it's a ribbon, there are paper type fabric ribbon that I have seen in stores, usually a cheap type of polyester, not quite paper, not quite fabric, the caker could have printed the image on edible paper and then done the top and bottom in royal icing.